Hydraulic jack



May 20, 1930. H, C, M|| R ET AL 1,759,516

HYDRAULIp JACK Filed July 5, 1928 Fn; Z

Patented May 20, 1930 STT' nir

1,759,5lii

HENRY CHIPMAN MILLER, OF LONDON, ENGLAND, AND GEORGE PERCY SUMNER, DE-

CEASED, LATE OF LONDON, ENG-LAND, BY MAY SUIVINER, EXECUTOR, OF MIDDLE- SEX, ENGLAND; SAIID MAY SMNER, EXECUTOR, ASSIGNGB TO SAID HENRY CHIP- MAN MILLER HYDRAULIC JACK Application :tiled July 5, 1928, Serial No. 290,584, and in Great Britain July 6, 1927.

This invention relates to improvements in hydraulic and other fiuid pressure jacks and like lifting and tipping machines oi the kind provided with overflow vents for the escape oi' excess of motive iiuid when aumping is continued after the ram has reached the e3:- tremity of its lift.

Objects of the present invention are to improve the construction of such overfiow vents so as to prevent damage -to the bucket leather of the ram and to facilitate the escape of motive iuid through the overflow vents.

Hydraulic jacks and like lifting and tipping machines of the kind referred to are provided with either single or multiple lift rams, the latter comprising two or more sections which telescope one within the other, while the lower sec-tion works in the ram cylinder.

n the case of a single lift ram one or more overflow vents or outlet passages are formed in the wall of the ram cylinder, while in the case of multiple lift rams comprising two or more telescoping sections, the overflow vents or outlet-s are usually formed in the wall of the tubular section in which the top lift of the ram telescopes.

In either case the overflow vents or outlets are arranged either in the ram cylinder or in one of the tubular ram sections so that such vents or passages are just uncovered by the lower edge of the bucket leather of the ram or ram section when the ram has reached the extremity of its lift, thus permitting` excess of motive fluid to escape through the overflow vents or passages.

Owing to the pressure of the escaping motive liuid the bucket leather of the ram or ram section tends to become split, shredded or otherwise camaged, the fragments being carried into the overflow vents or outlet passages and thus impede the escape of the motive fluid.

According to the present invention an annular groove or recess is formed in the bore of the ram cylinder or the tubular ram section in which the overiiow vents or outlet passages are arranged, so that the inner ends of such vents or outlets terminate in the annular groove or recess.

The annular groove or recess may be formed by means of a press or by rolling, turning, burnishing or otherwise, and is preferably shallow in proportion to the diameter of the overflow vents or outlet passages which terminate therein. Conveniently the depth of' the groove or recess is from one-fourth to one-half of the diameter of the vents or outlets, and its width approximately two to three times such diameter.

The invention is illustrated by way of eX- ample in the accompanying drawings wherein similar' reference numerals indicate like Figure l is a yfragmental vertical section illustrating one application of the invention to a hydraulic jack having a two-lift telescopic ram.

Figure 2 is a fragmental vertical section on an enlarged scale, and Figure?) a cross-secered by the bottom edge ot the bucket leather 9 of the top ram section 8 when the ram is at the extremity of its lift. The cup leather 9 is arranged in known manner above the perforated enlarged piston end 10 of the ram section 3, the perforations l1 in such piston end allowing the motive fluid to reach the cup 'leather 9 so that when the latter uncovers the overflow vents 4l excess of motive fluid escapes from the interior of the bottom ram section 2 in the event of overpumping.

In accordance with the present invention a shallow annular groove or recess 5 is formed in the bore of the bottom ram section 2 so that the inner ends of the vents or outlets 4 terminate in the annular groove or recess 5.

As the top ram sections 3 approaches the end of its lift, the cup leather 9 is forced into the shallow annular groove or recess 5 against which its outer surface is supported so that the lower edge of the cup leather can be drawn past the inner orifices 4a of the vents or outlets 4 without being split, shredded or other- Wise injured by the pressure of the motive fluid as it escapes through the vents or outlets.

The vents or outlets 4 are preferably flared outwardly as indicated, and may communicate with return passages 6 arranged in a sleeve or liner, or in the wall of the bottom ram section 2.

Figures 2 and 3 illustrate one application of the present invention to the cylinder of a single lift ram in which overflow vents or outlets are arranged.

As shown in these figures, 7 indicates the ram cylinder furnished with a suitable ram stop 8, and'4 the overflow vents or outlets, the inner ends 4aM of which terminate in the annular groove or recess 5 formed in the bore of the cylinder.

The annular groove or recess 5 is illustrated diagrammatically in the drawing, and may be of any preferred dimensions, but as indicated 'its depth is approximately half the diameter of the inner orifices 4LL of the overflow vents or outlets 4, and its width about three times such diameter.

The overflow vents or outlets 4, instead of being outwardly flared as indicated, may, if desired, be made parallel, while the annular groove or recess is conveniently formed by rolling, turning and burnishing the bore after the vents or outlets 4 have been formed in the wall thereof, so as to ensure maximum surface smoothness and density of material about the inner orifices 4a of the vents or outlets 4.

We claim l. In a fluid pressure lifting and tipping jack comprising a ram having a cup leather and operating in a cylinder furnished with overflow vents through which excess of motive fluid can escape from the cylinder when the ram is raised to the limit of its lift, the combination with the overflow vents of an annular groove formed in the bore of the cylinder (about the inner ends of said vents) so as to co-operate with and form a guide and support for the cup leather of the ram as such cup leather is drawn past said vents.

2. A fluid pressure lifting and tipping jack comprising a ram having two or more telescoping tubular sections, each having a cup leather, one of which sections is furnished with overflow vents through which excess of motive fluid can escape when the telescoping ram has reached the limit of its lift, wherein the inner ends of the overflow vents terminate in an annular groove formed in the bore of the tubular ram section in which said vents are arranged, substantially as described;

In testimony whereof we aflix our signahere; f 

